The invention relates to an electron tube having an electrode system centered in a tubular glass envelope portion by means of a number of metal spring elements which are connected to the electrode system. The elements each extend towards the wall of the envelope portion and press against the wall at a respective contact point.
Typical electron tubes of this type are cathode-ray tubes such as picture display tubes and camera tubes. The electrode system forms therein an electron gun for generating one or more electron beams. During manufacture of the tube, when the electrode system is inserted into the tubular envelope portion, the metal spring elements press against the glass wall of the envelope under pretension. Not infrequently damage in the form of scratches and crumbled glass particles occurs to the glass surface during sliding of the spring elements over the glass wall.
During the further manufacture of the tube such damage may lead to fracture of the glass, while the crumbled glass particles may land in places in the tube where they may seriously damage the quality of the operating tube.